Drill bit with deflector and interlock



May 12, 1964 3,132,708

J. L. STOCKARD, JR

DRILL BIT WITH DEFLECTOR AND INTERLOCK Filed July 28, 1961 INVENTOR JIIFSZ' Aji'wwea B YMM, f M

ATTORNEYS United States Patent 3,132,708 DRILL BET WITH DEFLECTOR AND INTERLOCK Jesse L. Stoclrard, In, Houston, Tex., assignor, by mesne assignments, to Hughes Tool Company, Houston, Tex.,

a corporation of Delaware Filed July 28, 1961, Ser. No. 127,552 9 Claims. (Cl. 175-412) The present invention relates to drilling bits and, more particularly, to improvements in detachable blade drilling bits and unitized drilling bits for use in drilling earth formations.

Detachable blade bits and unitized drilling bits of the type herein described are generally referred to in the well art as drag bits since the cutting action against the earth formation by the bit is accomplished by rotating the bit with a weight thereon so that the cutting edges of the blades drag against the formation and cut into the formation as the bit rotates.

When a drilling rig is drilling in a hard rock formation, approximately 20,000 to 30,000 pounds of weight is being exerted upon the formation by the rig through the drill stem and through the blades of the drag bit. Oftentimes during the course of drilling, the bit suddenly breaks through the hard rock formation into a softer strata below it, for example, into clay or shale. When this occurs, the tremendous force exerted upon the bit by the drilling rig and the drill stem causes the drilling bit to drive or advance 6 to 12 inches into the soft formation or strata before the driller can release the weight off the bit. Heretofore dificulty has been encountered when driving into a soft formation from a hard formation, as cuttings from the soft formation, such as clay or shale, are forced up into the water course thereby blocking the same and preventing the passage of the flushing fluid which is necessary for the removal of cuttings from the I well bore.

An object of the present invention is to provide a drag bit or the like having a plurality of blades including means thereon for preventing the clogging of the fluid passageway during the drilling operation, especially when the bit encounters a soft lower strata of clay or shale after drilling in a hard strata such as a rock formation.

Another object of the present invention is to provide a drilling bit with detachable blades and unitized bit having means on the front surface of the blades for deflecting and directing cuttings of the blades upwardly and outwardly away from the center of the bit.

Heretofore, a great deal of difliculty has been encountered in attempting to keep detachable blades of a drag drilling bit firmly secured in position on the bit body. The weight placed on the drill bit immediately above the same so that the bit is pushed downwardly against the formation as the bit is rotated creates tremendous forces in the individual blades causing fatigue and failure in the blade. Increases in bit footages, caused by improved design and resharpening, necessitate changes to relieve fatigue. Efforts have been made for overcoming this difficulty by interlocking the blades to each other by contact with one another to increase stability. However, such efforts have not completely overcome the difficulty as they merely obtain stability by trying to increase rigidity rather than by causing the forces exerted on one blade to be transferred to another blade at a different angle so that, in effect, the transferred forces are in a direction such that they tend to cancel at least a portion of the forces developed in the receiving blade through its cutting action.

Pursuant to the above, it is an ancillary object of the present invention to provide a drag type drilling bit having detachable blades with means for transferring the 3,132,708 Patented May 12., 1964 tion from that of the formation forces on such following blade to increase the overall stability of the bit.

Still another object of the present invention is to provide a drag type drilling bit having a plurality of detachable blades so constructed and arranged whereby stability in the bit is accomplished by makingthe blades substantially rigid with respect to one another and by the formation forces acting on one blade to the following blade in a direction different from that of the formation forces normally exerted on the following blade in reaction to its cutting action, thereby cancelling at least a portion of such formation forces on the following blade and permitting greater stress upon the bit without causing fatigue and failure to the blades of the bit.

These and other objects and advantages of the present invention will become more readily apparent from the fol lowing specification, claims and accompanying drawings in which:

FIGURE 1 is a partially exploded perspective view of a drag bit in which the present invention is embodied, only one of the blades being illustrated in its relative posi tion for purposes of clarity;

FIGURE 2 is an enlarged bottom plan view of the drilling bit of the present invention illustrating the means for deflecting cuttings as Well as the means for interlocking and transmitting forces from one blade to another;

FIGURE. 3 is an enlarged side elevational view illustrating the bit of'FIGURES l and 2 and showing the cooperation of the deflecting means and the means for interlocking and for transferring the forces from one blade to another blade;

FIGURE 4 is an elevational view of one of the blades of the drilling bit, the view being taken from a position looking at the front substantially planar surface of the blade and further showing the interior curved portion of the blade for use in attaching the blade to the drill bit body and FIGURE 5 is a section of the deflecting means and a portion of a blade onthe sectioning plane indicated in FIGURE 4, looking in the direction of the arrows 55.

Referring now to the drawings wherein like characters and reference numerals represent like or similar parts, the drill bit, which is generally indicated at 10, is best illustrated in FIGURE 1 in its relationship to a drill collar 12 and a retainer collar 14. The drill bit 10 comprises a body 16 having an externally threaded shank 18 with a tapered .portion 17 and a plurality of detachable blades 19 (only one being shown in FIGURE 1) detachably carried thereon. The body 16 is tubular as well as the drill collar 12 so that when the drill bit is in assembled relationship on the drill collar 12 and retainer collar 14, a passage 20 is provided for pumping a flushing fluid there through during the drilling operation.

Spaced upwardly from the lower end of the body 16 and immediately below the threaded shank 18 is a groove 22 on the outer periphery of the body. The portion of the body 16 which is not threaded is tapered as indicated at 17 and the interior surface 24 of the blade 19 is also provided with a taper complementary to the tapered portion 17 of the body 16. As best shown in FIGURE 4, a rib or ledge 26 is provided on the interior surface 24 of the blade 19, the rib 26 being adapted to be received within the groove 22 on the body 16 to prevent vertical movement of the blade as well as proper positioning of the blade" with respect to other blades when the bit is assembled.

The blades 19 are assembled about the body 16 with their ribs 26 in the groove 22 and then the retainer collar 14, which is provided with an internal taper corresponding to the external taper 28 of the blades 19, is fitted down 3 over the blades with the threaded shank 18 of body 16 extending out of the retainer collar 14. The drill collar 12, which is internally threaded at 30, is adapted to receive and engage the externally threaded shank 18, the end 32 of the retainer collar 14 engaging the end 34 of the drill collar 12 when the shank 18 is fully threaded into the drill collar.

While the drill bit illustrated in FIGURES 1 through 4 inclusive utilizes three blade, it will be understood that any number of blades may be used although generally the number of blades of a drag bit does not exceed four. Also, if desired, the body 16 may be provided with notches to accommodate a formed portion of the blade, as fully disclosed in the United States Patent No. 2,859,942, issued November 11, 1958, to Herbet J. Hawthorne.

The blades 19, which are identical in configuration, are best shown in detail in FIGURES 2, 3 and 4. The blades the water or other flushing fluid to get under the cuttings and between the face 36 of the blade and the cuttings. This technique of operation prevents clogging of the passageway 20 and permits continuous operation without withdrawal of the bit for the purpose of cleaning the passageway.

Referring to FIGURES 2, 3 and 4, it will be noted that at the lower end of the trailing or rear edge or surface 42 of each blade 19 beneath the concavely curved portion 44 is a small lug 52 on each blade 19. The lug 52 extends from the rear surface 42 toward the center line of the bit and when the blades 19 are in assembled relationship on the body 16, the lug 52 fits in behind and 19 are provided with a substantially planar front or cutting surface 36 which terminates in a plurality of stepped cut ting edges 38. These cutting edges 38 may also be referred to as cutting fingers and may be tungsten carbide inserts or integrally formed portions of a hardened steel blade. They may be retipped or resharpened when necessary. The cutting fingers 38 are provided on the back surface of the blade with upwardly curved rigid projections or ribs 40, FIGURES 2 and 3, fairing into the blade body, which affords some rigidity to the blade. Construction of the cutting fingers 38 and ribs 40 is somewhat similar to that disclosed in the aforementioned United States Patent 2,859,942. The blade 19 is provided with a rear or trailing edge 42 opposite the planar front surface 36. Edge 42 is concavely curved, as indicated at 44. When the blades are assembled on the body 16, the front surface 36 will engage the trailing edge or rear edge 42 of another bladeexcept in the area where the concavely curved surface 44 is provided. It will now be apparent that the opening between the adjacent blades, as identified by the numeral 46, provides an outlet for the water course or fluid passageway 20, there also being a space 48 centrally of the plurality of blades at a point adjacent the lowermost cutting surface 38.

Provided on the substantially planar front surface 36 of each blade in an area just above the stepped cutting surfaces 38 is a deflector lug 50. The deflector lug 50, which is preferably integrally formed with the blade, is elongated, as best shown in FIGURE 4, and extends upwardly and outwardly with respect to the lowermost point of the front or cutting surface 36 of the blade. In more detail, the deflector lug 50 has a longitudinal axis represented by the center line 51 in FIGURE 4, which extends at approximately 45 to the center line 54 of the assembled bit. Also, the deflector lug 50 extends outwardly from the planar surface 36 at an angle of approximately 70 with respect thereto, as shown in FIGURE 5. By pro viding the deflector lug 50 positioned above the cutting fingers 38 on the front substantially planar cutting surface 36 at the angles mentioned above, it has been found that cuttings from the cutting fingers are deflected upwardly and outwardly away from the openings 46 and 48 and thereby prevent clogging of the water course or flushing fluid passageway during the drilling operation. This feature of the present invention is particularly important when the drilling bit is being used to drill a hard rock-like formation and then suddenly breaks through the rock-like formation into a softer formation, for example, clay or shale. Under these conditions of operation, as soon as the drill bit breaks through the hard rock formation, the

contacts the deflector lug 50 at the deflector lugs innermost end. Forces developed in the blade 19 'due to the cutting action of the cutting fingers 38 are transferred through the lug 52 in a direction substantially normal to the cutting face to the innermost end of the deflector lug 50 of the immediately adjacent and following blade.

' deflector lug 50 is such that the direction of forces is substantially parallel to the cutting face 36 of such following blade. The forces transmitted to one blade 19 by the preceding blade 19 will be in a different direction to the forces created in the following blade by the cutting action of its cutting fingers 38. Consequently, the transfer of forces from one blade to another and changing the direction of the forces during the transfer of the same will tend to cancel at least some of the forces imposed by the formation in reaction to the cutting action of the blade, and greater stress can be applied to the bit without causing fatigue and failure of the blades 19 of the bit.

The improved drill bit heretofore described fully and effectively accomplishes the objects and advantages of the present invention. While the improved drill bit described herein illustrates the concept of the invention, it will be understood that the drill bit is susceptible to some modifications and changes without departing from the spirit and principles of the invention involved; Therefore, the terminology used in the specification is for the purpose of description and not limitation, the scope of the invention being defined in the claims.

What is claimed is:

1. A blade suitable for mounting on the body of a I drag bit together with other such blades and other bit tremendous weight of the drilling rig, drill stem and the parts to form an assembled drag bit suitable for rotary drilling, said blade having a substantially planar front surface, cutting fingers projecting downwardly in a substantial continuation of the planar front surface and a deflector lug on said planar front surface for deflecting cuttings from said cutting fingers coming across the planar front surface upwardly and away from the inner edge of said surface, said deflector lug being integral with the blade and elongated upwardly and outwardly to define an acute angle with the center line of said bit.

2. A blade suitable for mounting on the body of a drag bit together with other such blades and other bit parts to form an assembled drag bit suitable for rotary drilling, said blade having a substantially planar front surface, cutting fingers projecting downwardly in a substantial continuation of the planar front surface, an elongated deflector lug on said planar front surface for deflecting cuttings from said cutting fingers coming across said planar surface upwardly and away from the inner edge of said surface, and a lug on the inner edge of said blade adapted to contact the deflector lug of an adjacent blade in assembly to thereby transfer forces from said blade to said adjacent blade through the deflector lug of said adjacent blade in a direction different from I that of the formation forces on said adjacent blade.

3. The blade of claim 2 in which said deflector lug is elongated upwardly and outwardly to define an acute angle with the center line of said bit.

4. A drag type rotary drilling bit comprising: a body, a plurality of blades carried on said body, each of said blades having a substantially planar front surface with cutting fingers extending downwardly therefrom in a substantial continuation of the planar front surface, said blades and said body when assembled into the drilling bit having a flushing fluid passageway therethrough opening between adjacent blades, and an elongated deflector lug secured to and projecting outwardly from each said planar front surface of each of said blades for deflecting cuttings from said cutting fingers coming across the planar front surface of said blades upwardly and away from the bit center and the fluid passageway, said deflector lug being elongated upwardly and outwardly with respect to the center line of the bit to define an acute angle therewith.

5. A drag bit of the character described in claim 4 wherein the angle at which said lug extends relative to the center line of the bit is of the order of 45.

6. A drag bit of the character described in claim 5 wherein said deflector lug projects outwardly at an approximately 70 angle relative to the planar front surface of the blade.

7. A drag type rotary drilling bit comprising: a body, a plurality of blades detachably carried on said body, each of said blades having a substantially planar front surface with cutting fingers extending downwardly therefrom in a substantial continuation of the planar front surface, said blades and said body when assembled into the drilling bit having a flushing fluid passageway therethrough opening between adjacent blades, an elongated deflector lug on the front surface of each of said blades for deflecting cuttings from said cutting fingers coming across the planar front surface of said blades upwardly and away from the bit center and the fluid passageway, said elongated lug being integral with the blade and extending at an angle to the bit center line and to the blade face, and a lug provided on the rear inner edge of each of said blades extending toward the center line of the bit, said last-mentioned lug contacting the deflector lug of an adjacent blade at its innermost end to thereby transfer forces from one blade through said deflector lug to another blade in a difierent direction to the forces imposed upon said blades by the formation being drilled in reaction to the cutting action of said cutting fingers.

References Cited in the file of this patent UNITED STATES PATENTS Harrington Sept. 12, 1950 Skidmore et al. Apr. 4, 1961 Creel Jan. 29, 1963 

1. A BLADE SUITABLE FOR MOUNTING ON THE BODY OF A DRAG BIT TOGETHER WITH OTHER SUCH BLADES AND OTHER BIT PARTS TO FORM AN ASSEMBLED DRAG BIT SUITABLE FOR ROTARY DRILLING, SAID BLADE HAVING A SUBSTANTIALLY PLANAR FRONT SURFACE, CUTTING FINGERS PROJECTING DOWNWARDLY IN A SUBSTANTIAL CONTINUATION OF THE PLANAR FRONT SURFACE AND A DEFLECTOR LUG ON SAID PLANAR FRONT SURFACE FOR DEFLECTING CUTTINGS FROM SAID CUTTING FINGERS COMING ACROSS THE PLANAR FRONT SURFACE UPWARDLY AND AWAY FROM THE INNER EDGE OF SAID SURFACE, SAID DEFLECTOR LUG BEING INTEGRAL WITH THE BLADE AND ELONGATED UPWARDLY AND OUTWARDLY TO DEFINE AN ACUTE ANGLE WITH THE CENTER LINE OF SAID BIT. 